gnu/dist/texinfo/info/signals.c

   1 /*      $NetBSD$        */
   2
   3 /* signals.c -- install and maintain signal handlers.
   4    Id: signals.c,v 1.7 2004/04/11 17:56:46 karl Exp
   5
   6    Copyright (C) 1993, 1994, 1995, 1998, 2002, 2003, 2004 Free Software
   7    Foundation, Inc.
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 2, or (at your option)
  12    any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program; if not, write to the Free Software
  21    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  22
  23    Originally written by Brian Fox (bfox@ai.mit.edu). */
  24
  25 #include "info.h"
  26 #include "signals.h"
  27
  28 void initialize_info_signal_handler (void);
  29
  30 /* **************************************************************** */
  31 /*                                                                  */
  32 /*              Pretending That We Have POSIX Signals               */
  33 /*                                                                  */
  34 /* **************************************************************** */
  35
  36 #if !defined (HAVE_SIGPROCMASK) && defined (HAVE_SIGSETMASK)
  37 /* Perform OPERATION on NEWSET, perhaps leaving information in OLDSET. */
  38 static void
  39 sigprocmask (int operation, int *newset, int *oldset)
  40 {
  41   switch (operation)
  42     {
  43     case SIG_UNBLOCK:
  44       sigsetmask (sigblock (0) & ~(*newset));
  45       break;
  46
  47     case SIG_BLOCK:
  48       *oldset = sigblock (*newset);
  49       break;
  50
  51     case SIG_SETMASK:
  52       sigsetmask (*newset);
  53       break;
  54
  55     default:
  56       abort ();
  57     }
  58 }
  59 #endif /* !HAVE_SIGPROCMASK && HAVE_SIGSETMASK */
  60
  61 /* **************************************************************** */
  62 /*                                                                  */
  63 /*                  Signal Handling for Info                        */
  64 /*                                                                  */
  65 /* **************************************************************** */
  66
  67 #if defined (HAVE_SIGACTION) || defined (HAVE_SIGPROCMASK) ||\
  68   defined (HAVE_SIGSETMASK)
  69 static void
  70 mask_termsig (sigset_t *set)
  71 {
  72 # if defined (SIGTSTP)
  73   sigaddset (set, SIGTSTP);
  74   sigaddset (set, SIGTTOU);
  75   sigaddset (set, SIGTTIN);
  76 # endif
  77 # if defined (SIGWINCH)
  78   sigaddset (set, SIGWINCH);
  79 # endif
  80 #if defined (SIGQUIT)
  81   sigaddset (set, SIGQUIT);
  82 #endif
  83 #if defined (SIGINT)
  84   sigaddset (set, SIGINT);
  85 #endif
  86 # if defined (SIGUSR1)
  87   sigaddset (set, SIGUSR1);
  88 # endif
  89 }
  90 #endif /* HAVE_SIGACTION || HAVE_SIGPROCMASK || HAVE_SIGSETMASK */
  91
  92 static RETSIGTYPE info_signal_proc (int sig);
  93 #if defined (HAVE_SIGACTION)
  94 typedef struct sigaction signal_info;
  95 signal_info info_signal_handler;
  96
  97 static void
  98 set_termsig (int sig, signal_info *old)
  99 {
 100   sigaction (sig, &info_signal_handler, old);
 101 }
 102
 103 static void
 104 restore_termsig (int sig, const signal_info *saved)
 105 {
 106   sigaction (sig, saved, NULL);
 107 }
 108 #else /* !HAVE_SIGACTION */
 109 typedef RETSIGTYPE (*signal_info) ();
 110 #define set_termsig(sig, old) (void)(*(old) = signal (sig, info_signal_proc))
 111 #define restore_termsig(sig, saved) (void)signal (sig, *(saved))
 112 #define info_signal_handler info_signal_proc
 113 static int term_conf_busy = 0;
 114 #endif /* !HAVE_SIGACTION */
 115
 116 static signal_info old_TSTP, old_TTOU, old_TTIN;
 117 static signal_info old_WINCH, old_INT, old_USR1;
 118 static signal_info old_QUIT;
 119
 120 void
 121 initialize_info_signal_handler (void)
 122 {
 123 #ifdef SA_NOCLDSTOP
 124   /* (Based on info from Paul Eggert found in coreutils.)  Don't use
 125      HAVE_SIGACTION to decide whether to use the sa_handler, sa_flags,
 126      sa_mask members, as some systems (Solaris 7+) don't define them.  Use
 127      SA_NOCLDSTOP instead; it's been part of POSIX.1 since day 1 (in 1988).  */
 128   info_signal_handler.sa_handler = info_signal_proc;
 129   info_signal_handler.sa_flags = 0;
 130   mask_termsig (&info_signal_handler.sa_mask);
 131 #endif /* SA_NOCLDSTOP */
 132
 133 #if defined (SIGTSTP)
 134   set_termsig (SIGTSTP, &old_TSTP);
 135   set_termsig (SIGTTOU, &old_TTOU);
 136   set_termsig (SIGTTIN, &old_TTIN);
 137 #endif /* SIGTSTP */
 138
 139 #if defined (SIGWINCH)
 140   set_termsig (SIGWINCH, &old_WINCH);
 141 #endif
 142
 143 #if defined (SIGQUIT)
 144   set_termsig (SIGQUIT, &old_QUIT);
 145 #endif
 146
 147 #if defined (SIGINT)
 148   set_termsig (SIGINT, &old_INT);
 149 #endif
 150
 151 #if defined (SIGUSR1)
 152   /* Used by DJGPP to simulate SIGTSTP on Ctrl-Z.  */
 153   set_termsig (SIGUSR1, &old_USR1);
 154 #endif
 155 }
 156
 157 static void
 158 redisplay_after_signal (void)
 159 {
 160   terminal_clear_screen ();
 161   display_clear_display (the_display);
 162   window_mark_chain (windows, W_UpdateWindow);
 163   display_update_display (windows);
 164   display_cursor_at_point (active_window);
 165   fflush (stdout);
 166 }
 167
 168 static void
 169 reset_info_window_sizes (void)
 170 {
 171   terminal_goto_xy (0, 0);
 172   fflush (stdout);
 173   terminal_unprep_terminal ();
 174   terminal_get_screen_size ();
 175   terminal_prep_terminal ();
 176   display_initialize_display (screenwidth, screenheight);
 177   window_new_screen_size (screenwidth, screenheight);
 178   redisplay_after_signal ();
 179 }
 180
 181 static RETSIGTYPE
 182 info_signal_proc (int sig)
 183 {
 184   signal_info *old_signal_handler = NULL;
 185
 186 #if !defined (HAVE_SIGACTION)
 187   /* best effort: first increment this counter and later block signals */
 188   if (term_conf_busy)
 189     return;
 190   term_conf_busy++;
 191 #if defined (HAVE_SIGPROCMASK) || defined (HAVE_SIGSETMASK)
 192     {
 193       sigset_t nvar, ovar;
 194       sigemptyset (&nvar);
 195       mask_termsig (&nvar);
 196       sigprocmask (SIG_BLOCK, &nvar, &ovar);
 197     }
 198 #endif /* HAVE_SIGPROCMASK || HAVE_SIGSETMASK */
 199 #endif /* !HAVE_SIGACTION */
 200   switch (sig)
 201     {
 202 #if defined (SIGTSTP)
 203     case SIGTSTP:
 204     case SIGTTOU:
 205     case SIGTTIN:
 206 #endif
 207 #if defined (SIGQUIT)
 208     case SIGQUIT:
 209 #endif
 210 #if defined (SIGINT)
 211     case SIGINT:
 212 #endif
 213       {
 214 #if defined (SIGTSTP)
 215         if (sig == SIGTSTP)
 216           old_signal_handler = &old_TSTP;
 217         if (sig == SIGTTOU)
 218           old_signal_handler = &old_TTOU;
 219         if (sig == SIGTTIN)
 220           old_signal_handler = &old_TTIN;
 221 #endif /* SIGTSTP */
 222 #if defined (SIGQUIT)
 223         if (sig == SIGQUIT)
 224           old_signal_handler = &old_QUIT;
 225 #endif /* SIGQUIT */
 226 #if defined (SIGINT)
 227         if (sig == SIGINT)
 228           old_signal_handler = &old_INT;
 229 #endif /* SIGINT */
 230
 231         /* For stop signals, restore the terminal IO, leave the cursor
 232            at the bottom of the window, and stop us. */
 233         terminal_goto_xy (0, screenheight - 1);
 234         terminal_clear_to_eol ();
 235         fflush (stdout);
 236         terminal_unprep_terminal ();
 237         restore_termsig (sig, old_signal_handler);
 238         UNBLOCK_SIGNAL (sig);
 239         kill (getpid (), sig);
 240
 241         /* The program is returning now.  Restore our signal handler,
 242            turn on terminal handling, redraw the screen, and place the
 243            cursor where it belongs. */
 244         terminal_prep_terminal ();
 245         set_termsig (sig, old_signal_handler);
 246         /* window size might be changed while sleeping */
 247         reset_info_window_sizes ();
 248       }
 249       break;
 250
 251 #if defined (SIGWINCH) || defined (SIGUSR1)
 252 #ifdef SIGWINCH
 253     case SIGWINCH:
 254 #endif
 255 #ifdef SIGUSR1
 256     case SIGUSR1:
 257 #endif
 258       {
 259         /* Turn off terminal IO, tell our parent that the window has changed,
 260            then reinitialize the terminal and rebuild our windows. */
 261 #ifdef SIGWINCH
 262         if (sig == SIGWINCH)
 263           old_signal_handler = &old_WINCH;
 264 #endif
 265 #ifdef SIGUSR1
 266         if (sig == SIGUSR1)
 267           old_signal_handler = &old_USR1;
 268 #endif
 269         terminal_goto_xy (0, 0);
 270         fflush (stdout);
 271         terminal_unprep_terminal (); /* needless? */
 272         restore_termsig (sig, old_signal_handler);
 273         UNBLOCK_SIGNAL (sig);
 274         kill (getpid (), sig);
 275
 276         /* After our old signal handler returns... */
 277         set_termsig (sig, old_signal_handler); /* needless? */
 278         terminal_prep_terminal ();
 279         reset_info_window_sizes ();
 280       }
 281       break;
 282 #endif /* SIGWINCH || SIGUSR1 */
 283     }
 284 #if !defined (HAVE_SIGACTION)
 285   /* at this time it is safer to perform unblock after decrement */
 286   term_conf_busy--;
 287 #if defined (HAVE_SIGPROCMASK) || defined (HAVE_SIGSETMASK)
 288     {
 289       sigset_t nvar, ovar;
 290       sigemptyset (&nvar);
 291       mask_termsig (&nvar);
 292       sigprocmask (SIG_UNBLOCK, &nvar, &ovar);
 293     }
 294 #endif /* HAVE_SIGPROCMASK || HAVE_SIGSETMASK */
 295 #endif /* !HAVE_SIGACTION */
 296 }
 297 /* vim: set sw=2 cino={1s>2sn-s^-se-s: */